NKG2D and CD94 bind to multimeric α2,3-linked N-acetylneuraminic acid

Abstract Killer lectin-like receptors on natural killer cells mediate cytotoxicity through glycans on target cells including the sialyl Lewis X antigen (sLeX). We investigated whether NK group 2D (NKG2D) and CD94 can bind to sialylated N-linked glycans, using recombinant glutathione S -transferase-fused extracellular lectin-like domains of NKG2D (rNKG2Dlec) and CD94 (rCD94lec). Both rNKG2Dlec and rCD94lec bound to plates coated with high-sLeX-expressing transferrin secreted by HepG2 cells (HepTF). The binding of rNKG2Dlec and rCD94lec to HepTF was markedly suppressed by treatment of HepTF with neuraminidase and in the presence of N -acetylneuraminic acid. Moreover, rNKG2Dlec and rCD94lec bound to α2,3-sialylated human α 1 -acid glycoprotein (AGP) but not to α2,6-sialylated AGP. Mutagenesis revealed that 152 Y of NKG2D and 144 F and 160 N of CD94 were critical for HepTF binding. This is the first report that NKG2D and CD94 bind to α2,3-sialylated but not to α2,6-sialylated multi-antennary N -glycans.